In both cases,
the bound Nilsson orbital for \(\beta _2 = 0.3\)  associated with the \(2p_{3/2}\)  shell (1/2[310]) shows a characteristic halo tail at large distances
compared to those associated with the \(1d_{3/2}\)  shell (3/2[202], 1/2[211]).
As shown in Fig.REF , the last two valence nucleons occupy the orbital 3/2[202] at \(\beta _2=0.3\)  and there is no halo phenomena. With the increase of \(\beta _{2}\) , the orbital 1/2[310] will gradually fall down, and the orbital 3/2[202] will rise. The last two valence nucleons will occupy the halo orbit 1/2[310], and the halo phenomena will appear in the larger deformation range.
These results are in agreement with the observed halo in \(^{29}\) F [1]} and the predicted halo in \(^{31}\) F [2]}.
